Pharmacology Flashcards
What is the mechanism of penicillin?
Binds to penicillin binding proteins and inhibits transpeptidase rxn and cross linking of peptidoglycans
What are some adverse effects of penicillin?
hypersensitivity: hives, shortness of breath, anaphylactic shock, or mild-rash
diarrhea
superinfections
What bacteria are sensitive to Penicillin G?
Streptococci and meningococci. Gram negative bacteria’s outer membrane limits entry of drug.
What are examples of antibiotics to treat penicillinase resistant staphylococci? (excluding MRSA)
Nafcillin and Dicloxacillin
What is amoxicillin the drug of choice for?
otitis media, can be combined with clavulanate (beta lactamase inhibitor)
What is ampicillin the drug of choice for?
Meningitis and other infections caused by Listeria monocytogenes. Often used with sulbactam (beta lactamase inhibitor)
What would you use as a surgical prophylaxis against staphylococci?
Cefazolin - 1st gen cephalosporin
What would you use to treat otitis media, when H. influenza is resistant to amoxicillin? What is this antibiotic also used to treat?
Cefprozil. Also treats community acquired pneumonia.
What are the drugs of choice for treating meningitis and gonorrhea caused by Neisseria?
Ceftriaxone (good for gonorrhea) or cefotaxime - 3rd gen cephalosporins
What is the mechanism of vancomycin?
A tricyclic glycopeptide that binds irreversibly to acyl-D-ala-D-ala terminus of peptidoglycan precursor. Inhibits crosslinking and membrane pore formation.
What is vancomycin used to treat?
- MRSA s. aureus. + other gram + bacteria
- patients allergic to penicillins
- enterococcal endocarditis
- psedumembraneous colitis caused by C. difficult
What are the adverse effects of vancomycin?
- infusion related toxicity
- red man syndrome due to histamine release
- ototoxicity at higher concentration
- enhances nephrotoxicity of amino glycosides and amphotericin B
What is the mechanism of amino glycosides?
They bind to 30S ribosomal subunit and interfere with initiation of protein synthesis. Cause misreading of genetic code, wrong amino acid is inserted into proteins. Results in post-antibiotic effect.
-synergistic with penicillins and vancomycin, which makes pores in bacterial cell wall for amino glycosides to enter.
What are adverse effects of aminoglycosides?
- Renal toxicity: most common cause of drug induced renal failure
- Ototoxicity: cochlear toxicity (irreversible) and vestibular toxicity
What is gentamicin used for? What class of antibiotics is it?
enterococcal and staphylococcal infection, viridans group strep infection (endocarditis). Aminoglycoside. not orally absorbed.
What is neomycin used for? What class of antibiotics is it?
Sometimes taken orally to treat hepatic coma and GI infections, for surgical prophylaxis in colorectal surgeries. Also used topically to treat skin infections (Neosporin).
What is the mechanism behind tetracyclines?
competitively block binding of tRNA to 30S subunit and prevent addition of new amino acids to growing peptide chain. Reversible.
What are the adverse effects of tetracyclines?
- epigastric distress-irritates gastric mucosa
- calcified tissues-bind to calcifying teeth and bones. Contraindicated in children under 8, pregnant women, and nursing mothers
- nephrotoxicity
- phototoxicity - sunburn
Describe the pharmacokinetics of tetracyclines.
- oral bioavailability reduced if ingested with products containing metals, e.g. dairy products, antacids, iron supplements
- mostly excreted in urine except doxycycline excreted in bile
What are the clinical uses of tetracyclines?
- Rickettsia infections -Rocky Mtn Spotted fever
- Lyme disease - Borrelia burgdorferi
- Mycoplasma pneumonia
- Chlamydia trachomatis
- Acne vulgaris
- Shorten chloera therapy
List two examples of tetracyclines.
Tetracycline and doxycycline
What is the mechanism behind macrolides?
- Bind to 50S subunit and prevent translocation of peptide from A site to P site
- Block peptidyl transferase, the enzyme that catalyzes formation of peptide bond between new amino acid and nascent peptide
- bacteriostatic
List two examples of macrolides.
Erythromycin and Azithromycin.
What are the adverse effects of macrolides?
- Epigastric distress (mainly erythromycin) - stimulates GI motility
- cholestatic jaundice - caused by hypersensitivity rxns
- ototoxicity
contraindications: not given to patients with hepatic dysfunction
Describe pharmacokinetics of macrolides?
- Don’t enter CSF
- Erythromycin and azithromycin excreted by bile
- diffuse into prostatic fluid
What are the clinical uses of macrolides?
- gram + mainly
- prophylaxis and treatment of pneumonia
- chlamydia trachomatis PID
- Otitis media of H. influenzae
- Peptic ulcer from H. pylori
What is the mechanism behind sulfonamides?
-inhibit dihydropteorate synthase and decrease levels of dihydrofolic acid in bacteria due to similarity to PABA
What is an example of a sulfonamide?
Sulfamethoxazole.